pagespeed/system/system_thread_system.h

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

//
// A wrapper around PthreadThreadSystem that takes care of some signal masking
// issues that arise in forking servers.  We prefer pthreads to APR as APR
// mutex, etc., creation requires pools which are generally thread unsafe,
// introducing some additional risks.

#ifndef PAGESPEED_SYSTEM_SYSTEM_THREAD_SYSTEM_H_
#define PAGESPEED_SYSTEM_SYSTEM_THREAD_SYSTEM_H_

#include "pagespeed/kernel/base/basictypes.h"
#include "pagespeed/kernel/thread/pthread_thread_system.h"

namespace net_instaweb {

class SystemThreadSystem : public PthreadThreadSystem {
 public:
  SystemThreadSystem();
  virtual ~SystemThreadSystem();

  // It's not safe to start threads in a process that will later fork.  In order
  // to enforce this, call PermitThreadStarting() in the child process right
  // after forking, and DCHECK-fail if something tries to start a thread before
  // then.
  void PermitThreadStarting();

 protected:
  virtual void BeforeThreadRunHook();

 private:
  bool may_start_threads_;

  DISALLOW_COPY_AND_ASSIGN(SystemThreadSystem);
};

}  // namespace net_instaweb

#endif  // PAGESPEED_SYSTEM_SYSTEM_THREAD_SYSTEM_H_